1. Field of the Invention
The present invention relates to a light guide plate used for display devices, and an apparatus and method for manufacturing the same.
2. Discussion of the Related Art
Recently, flat panel display devices that can decrease a weight and a volume corresponding to the limitations of cathode ray tubes (CRTs) are being developed. Liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission display (FED) devices, and light emitting display devices are actively being researched as flat type display devices. However, among such flat panel display devices, LCD devices are easily manufactured, have good drivability of drivers, realize a high-quality image, and thus are attracting much attention.
Since LCD devices are driven with a low operating voltage, the LCD devices have low power consumption and are used as portable devices. Accordingly, the LCD devices are widely applied to various fields such as notebook computers, monitors, spacecrafts, airplanes, etc.
LCD devices include a liquid crystal panel that includes a lower substrate, an upper substrate, and a liquid crystal layer formed between the lower substrate and the upper substrate. In the LCD devices, the alignment of liquid crystal in the liquid crystal layer is adjusted with an electric field, and thus, light transmittance of the liquid crystal layer is adjusted, thereby displaying an image.
Unlike the other flat panel display devices, the LCD devices non-emitting display devices, and thus, a backlight unit is disposed as a light source in the rear of the liquid crystal panel. The backlight unit is largely categorized into a direct-type backlight unit and an edge-type backlight unit.
In the direct-type backlight unit, the light source is disposed in the rear of the liquid crystal panel, and light emitted from the light source is directly transferred to the liquid crystal panel. In the edge-type backlight unit, the light source is disposed in one side of the rear of the liquid crystal panel, and light emitted from the light source is transferred to the liquid crystal panel through the light guide plate.
The light guide plate changes a light path such that light emitted from a light source disposed at one side is transferred to the liquid crystal panel disposed in the front of the light guide plate. To this end, a plurality of patterns that changes a refractive angle of light to transfer light to the front of the light guide plate is disposed at a bottom of the light guide plate.
FIG. 1 is a sectional view illustrating a backlight unit including a light guide plate manufactured by a related art manufacturing method.
As illustrated in FIG. 1, the backlight unit includes a light guide plate 10 and at least one light emitting diode (LED) 20.
The LED 20 acts as the light source of the backlight unit.
The light guide plate 10 is disposed in order for one side surface thereof to face the LED 20. The light guide plate 10 changes a light path such that light emitted from the LED 20 is supplied to a liquid crystal panel (not shown).
A plurality of patterns 11 are formed at a lower side surface of the light guide plate 10. The patterns 11 are formed in the light guide plate 10 by a printing process or an imprinting process. The printing process forms the patterns 11 by printing a printing ink on the light guide plate 10 along a pattern. The imprinting process forms the patterns 11 by duplicating resin on the light guide plate 10 along a pattern.
In the light guide plate 10 manufactured by the related art manufacturing method, residual materials are left in respective portions in which the patterns 11 are formed. When the light guide plate 10 is manufactured by a screen printing process, printing inks are left in the light guide plate 10, thereby forming the patterns 11. When the light guide plate 10 is manufactured by the imprinting process, resins are left in the light guide plate 10, thereby forming the patterns 11. The printing inks or resins left in the light guide plate 10 partially absorb light emitted from the LED 20, causing the loss of light emitted from the LED 20. For this reason, the light guide plate 10 manufactured by the related art manufacturing method has a limitation in that efficiency of light (emitted from the LED 20) supplied to the liquid crystal panel is reduced. Furthermore, the light guide plate 10 manufactured by the related art manufacturing method decreases the light efficiency of the backlight unit, and thus degrades quality of an image displayed by a display device.